Problem: Solve for $x$ : $3x + 8 = 10x + 9$
Subtract $3x$ from both sides: $(3x + 8) - 3x = (10x + 9) - 3x$ $8 = 7x + 9$ Subtract $9$ from both sides: $8 - 9 = (7x + 9) - 9$ $-1 = 7x$ Divide both sides by $7$ $\dfrac{-1}{7} = \dfrac{7x}{7}$ Simplify. $-\dfrac{1}{7} = x$